1. Field of the Invention
The present invention relates to a closure of the threaded closure type, capable of being removably mounted on a container, particularly in the form of a glass jar, a bottle, a pot or some other shape. The invention is specifically suited to the closure of glass jars such as those used for packaging cosmetic care creams.
2. Description of the Related Art
In the field of cosmetics, particularly in the field of care creams, it is relatively commonplace to make use of glass jars. These jars are generally closed by a plastic lid having a screw thread capable of cooperating with a corresponding screw thread provided on an external surface of the jar in the vicinity of an opening delimited by a free edge.
One of the problems encountered with this type of packaging arises due to the large clearance existing between the jar and its plastic cap, which clearance is essentially due to the manufacturing tolerances of the glass screw thread, which are very wide. Such clearance leads to problems with the airtightness and keeping of the cream contained in the jar. Furthermore, it is not very well received by the consumers.
Thus, one of the objects of the invention is to provide a closure which completely or partially solves the problems discussed above with reference to the conventional devices.
Another object of the invention is to provide a closure, particularly for a glass container, which is able to compensate for the wide manufacturing tolerances on the glass.
It is a further object of the invention to provide a closure which is simple and economical to manufacture, particularly by molding.
According to a first aspect of the invention, these and other objects are achieved by a closure comprising a first screw thread capable of cooperating with a second screw thread defined by a container intended to receive said closure. It includes an elastically deformed part capable, when the first and second screw threads are engaged, of keeping the closure bearing elastically on the container in at least one direction which is oriented radially with respect to the closure, so as to improve the holding of the closure on the container. Thus, these elastically deformed parts make it possible to compensate for the wide tolerances arising in producing the screw thread borne by the container, particularly when this container is a glass container.
Advantageously, the elastically deformed parts are capable, when the first and second screw threads are engaged, of retaining at least one portion of the first screw thread bearing elastically on at least one corresponding portion of the second screw thread. The presence of these elastically deformed parts xe2x80x9clocksxe2x80x9d the screw thread when the closure is being screwed on and unscrewed. In other words, it is possible to obtain zero or practically zero functional clearance, thus substantially improving the packing qualities.
In a particular embodiment, the closure comprises a lateral skirt bearing the first screw thread, the elastically deformed part consisting of at least one elastically deformed portion of the skirt whose radius of curvature, at rest, differs from the radius of curvature of the remainder of the skirt. In such a configuration, the first screw thread is preferably produced on the interior wall of the lateral skirt, so that it can be engaged with the second screw thread borne by the exterior wall of a neck formed by the container.
Preferably the elastically deformed parts consist of at least one xe2x80x9cflatxe2x80x9d formed by the skirt. Such a flat may, in the case of a closure which is obtained by molding a thermoplastic, be obtained by deforming the lateral skirt as it leaves the mold and before the material has completely cooled. According to an advantageous alternative, the flat is also obtained directly at the time of molding, by giving the mold the appropriate shape.
Preferably, the closure has two diametrically opposed elastically deformed parts. By achieving such symmetry, the holding of the closure on the container is improved and, in particular, the closure is better centered on the container. The comfort experienced in opening and closing it is thus appreciably improved.
In another specific embodiment, the closure comprises a transverse wall, one edge of which is bent at 90xc2x0 to form the lateral skirt bearing the first screw thread. Such a structure helps in improving airtightness upon closure.
Preferably, each of the elastically deformed part is delimited at least in part by a slot formed in the lateral skirt in the vicinity of the transverse wall. Thus, each slot is associated with an elastically deformed band. Each of the elastically deformed parts extends along the entire angular width of the corresponding slot, and is delimited by one edge of the slot and by the free edge of the lateral skirt which lies facing the slot.
Also, the lateral skirt preferably comprises at least two diametrically opposed angular portions which have no screw thread. An arrangement of this kind allows for easy mold-release of the closure by allowing a mold made in three parts, namely a central part lying facing the thread-free parts, and two lateral parts. Mold release is achieved by first withdrawing the central part and by then bringing the two lateral parts closer together, so as to allow the threaded parts of the closure to be released from the mold.
In a particularly advantageous embodiment, the closure comprises two slots situated outside of the angular portions which have no screw thread. Advantageously, the two slots are diametrically opposed. Advantageously also, the two slots are centered on an axis substantially perpendicular to an axis on which are centered the two portions which have no screw thread. These two slots can be released from the mold as the two lateral parts of the mold are brought closer together.
In the case of a closure which is obtained by molding, it may be made of a thermoplastic, particularly a polyethylene or a polypropylene.
The closure may be covered with an outer covering whose function is mainly aesthetic, particularly to conceal the slots made in the lateral skirt of the closure. Furthermore, the outer covering makes it possible to increase the rigidity of the structure bearing the screw thread. This covering also allows the use of materials whose aesthetics are particularly well-suited to applications such as the field of cosmetics. The closure may be rendered integral with the outer covering by any appropriate technique, particularly by bonding, welding or snap-fastening.
According to a second aspect of the invention, there is also provided a container comprising a closure according to the first aspect.
Advantageously, the container is made of glass. It may, in particular, be a jar intended for packaging a care cream.